Wireless charging apparatus and wireless charging method

ABSTRACT

A wireless charging apparatus and a wireless charging method are provided. The method includes selecting at least one of a wireless power reception mode and a wireless power transmission mode by a wireless charging apparatus, wirelessly receiving electric power when the wireless power reception mode is selected, and wirelessly transmitting electric power when the wireless power transmission mode is selected.

PRIORITY

This application claims priority under 35 U.S.C. §119(a) to KoreanApplication Serial No. 10-2013-0141565 filed in the Korean IntellectualProperty Office on Nov. 20, 2013, the entire content of which isincorporated herein by reference.

BACKGROUND

1. Field of Invention

The present invention relates generally to wireless charging technology.

2. Description of Related Art

Mobile terminals, such as a mobile phone, a Personal Digital Assistant(PDA) and the like, are driven with rechargeable batteries and thebattery of the mobile terminal is charged through supplied electronicenergy by using a separate charging apparatus. Typically, the chargingapparatus and the battery have separate contact terminals at an exteriorof each and are electrically connected with each other by contacting thecontact terminals.

However, since the contact terminal outwardly protrudes in such acontact type charging scheme, the contact terminal is easilycontaminated by foreign substances and thus battery charging is notcorrectly performed. Further, battery charging may also not be correctlyperformed in a case where the contact terminal is exposed to moisture.

Recently, a wireless charging or a non-contact charging technology hasbeen developed and used for electronic devices to solve theabove-mentioned problem.

Such a wireless charging technology employs wireless electric powertransmission/reception, and corresponds to, for example, a system inwhich a battery can be automatically charged when a portable phone isnot connected to a separate charging connector but instead, merelyplaced on a charging pad. The wireless charging technology is applied toa wireless electric toothbrush or a wireless electric razor and is wellknown to the public. Accordingly, a waterproof function can be improvedsince electronic products are wirelessly charged through the wirelesscharging technology, and the portability of electronic devices can beincreased since there is no need to provide a wired charging apparatus.Technologies related to the wireless charging technology are expected tobe significantly developed in the coming age of electric cars.

The wireless charging technology includes an electromagnetic inductionscheme using a coil, a resonance scheme using a resonance, and anRF/microwave radiation scheme converting electrical energy to amicrowave and then transmitting the microwave.

It is considered up to now that the electromagnetic induction scheme ismainstream, but it is expected that the day will come in the near futurewhen all electronic products are wirelessly charged, anytime andanywhere, on the strength of recent successful experiments forwirelessly transmitting power to a destination spaced away by dozens ofmeters through the use of microwaves at home and abroad.

A power transmission method through the electromagnetic inductioncorresponds to a scheme of transmitting electric power between a firstcoil and a second coil. When a magnet is moved in a coil, inductioncurrent is generated. By using the induction current, a magnetic fieldis generated at a transmission side, and electric current is inducedaccording to a change of the magnetic field so as to make energy at areception side. The phenomenon is referred to as magnetic induction, andthe electric power transmission method using magnetic induction has highenergy transmission efficiency.

The resonance method was released as a coupled mode theory, and uses aconcept of physics in which if a tuning fork is rung, a wine glass nearthe turning fork is also rung at the same frequency. Electromagneticwave containing electrical energy have also been made to resonateinstead of making sounds resonate. The resonated electrical energy isdirectly transferred only when there is a device having a resonancefrequency and parts of electrical energy which are not used arereabsorbed into an electromagnetic field instead of being spread in theair, so that the electrical energy does not affect surrounding machinesor people unlike other electromagnetic waves.

In the wireless charging system according to the conventional art, awireless power transmitter is fixedly installed at a site whileexternally receiving electric power to transmit electric power, but notto receive electric power. In addition, the wireless power transmitteraccording to the conventional art cannot be carried by the user, andcannot transmit electric power without an external power source.

SUMMARY

The present invention has been made to address at least the problems anddisadvantages described above, and to provide at least the advantagesdescribed below.

Accordingly, an aspect of the present invention is to provide a wirelesscharging apparatus using the wireless power transmission technology.

Accordingly, another aspect of the present invention is to provide awireless charging method and apparatus which can perform both wirelesspower transmission and wireless power reception and which can transmitand receive electric power while being carried by a user without usingan external power source.

Accordingly, another aspect of the present invention is to provide awireless charging apparatus which can not only transmit and receiveelectric power, but can also relay electric power between the wirelesscharging apparatus and another wireless charging apparatus, and whichcan charge another wireless charging apparatus when getting closer tothe other wireless charging apparatus.

In accordance with an aspect of the present invention, a wirelesscharging method is provided. The method includes selecting at least oneof a wireless power reception mode and a wireless power transmissionmode by a wireless charging apparatus, wirelessly receiving electricpower when the wireless power reception mode is selected, and wirelesslytransmitting electric power when the wireless power transmission mode isselected.

In accordance with another aspect of the present invention, a wirelesscharging apparatus is provided. The wireless charging apparatus includesa resonator, a wireless power transceiver, and a control. The wirelesspower transceiver includes a wireless power transmitter configured toperform any one of wireless power reception and wireless powertransmission through the resonator, based on a selection of at least oneof a wireless power reception mode and a wireless power transmissionmode. The controller is configured to, when the wireless power receptionmode is selected, control such that electric power is wirelesslyreceived, and when the wireless power transmission mode is selected,control such that the electric power is wirelessly transmitted.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentinvention will be more apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a block diagram illustrating a concept view of a wirelesscharging apparatus, according to an embodiment of the present invention;

FIG. 2 is a detailed block diagram of a wireless power transceiver (TRX)module of a wireless charging apparatus, according to an embodiment ofthe present invention;

FIG. 3 is a block diagram of a wireless power receiver (RX) unit and awireless power transmitter unit of a TRX module of a wireless chargingapparatus, according to an embodiment of the present invention;

FIG. 4 is a flowchart of an operation of a wireless charging apparatus,according to an embodiment of the present invention;

FIGS. 5 to 7 are block diagrams illustrating an example of a secondswitch of a TRX module of a wireless charging apparatus, according to anembodiment of the present invention;

FIGS. 8 and 9 are block diagrams illustrating an example of a firstswitch of a TRX module of a wireless charging apparatus, according to anembodiment of the present invention; and

FIG. 10 is a block diagram illustrating a charging operation between aplurality of wireless charging apparatuses, according to an embodimentof the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE PRESENT INVENTION

Hereinafter, various embodiments of the present invention will bedescribed in more detail with reference to the accompanying drawings. Itshould be noted that the same components of the drawings are designatedby the same reference numeral throughout. In the following descriptionof the present invention, a detailed description of known functions andconfigurations will be omitted when it may make the subject matter ofthe present invention unclear.

According to an embodiment of the present invention, a wireless chargingapparatus selectively performs wireless power transmission, wirelesspower reception, and wireless power relay, is implemented by a devicesuch as a wireless charging pad or a wireless charging terminal, andselectively receives external power, for example, external DC power, toselectively perform wireless power transmission, wireless powerreception, and wireless power relay or receives electric power from abattery to selectively perform wireless power transmission, wirelesspower reception, and wireless power relay.

FIG. 1 is a block diagram illustrating a concept view of a wirelesscharging apparatus, according to an embodiment of the present invention.

Referring to FIG. 1, the wireless charging apparatus 100 includes acontroller 110, a communication unit 120, a transceiver (TRX) module130, a resonance unit 140, and a battery 150.

The controller 110 controls an overall operation of the electronicdevice 100. For example, the controller 110 controls the overalloperation of the wireless charging apparatus 100 by using an algorithm,a program, or an application, required for the control, read from thestorage unit 112. The controller 110 is implemented in a form of aCentral Processing Unit (CPU), a microprocessor, or a mini computer.

According to the embodiment of the present invention, the controller 110makes a control to selectively perform wireless power reception,wireless power relay, and wireless power transmission. When wirelesspower reception is selected, the controller 110 makes a control toreceive wireless electric power through the TRX module 130. Whenwireless power relay is selected, the controller 110 makes a control torelay wireless electric power through the TRX module 130. When wirelesspower transmission is selected, the controller 110 makes a control totransmit wireless electric power through the TRX module 130. Thecontroller 110 determines whether electric power is to be wirelesslytransmitted by using electric power supplied from an external powersource (DC) or is to be wirelessly transmitted by using electric powerprovided through a battery 150 when electric power is wirelesslytransmitted.

The communication unit 120 performs communications with another wirelesscharging apparatus, a wireless power transmitter, or a wireless powerreceiver through a predetermined method. The communication unit 120performs communications with another wireless charging apparatus, awireless power transmitter, or a wireless power receiver through NearField Communication (NFC), ZigBee communication, infrared raycommunication, visual ray communication, Bluetooth communication, or aBluetooth Low Energy (BLE) method. The communication unit 120 may use aCSMA/CA algorithm. The above mentioned communication schemes are simplyexemplary, and the scope of the present invention is not limited by aspecific communication scheme which is performed by the communicationunit 120.

The communication unit 120 transmits a signal for information of thewireless charging apparatus 100. When the wireless charging apparatus100 performs wireless power reception, the communication unit 120transmits a wireless power transmission request signal to anotherwireless charging apparatus or a wireless power transmitter located nearthe wireless charging apparatus of the present invention. When thewireless charging apparatus 100 performs wireless power relay, thecommunication unit 120 transmits a wireless power transmission requestsignal to another wireless charging apparatus, a wireless powertransmitter or a wireless power receiver located near the wirelesscharging apparatus of the present invention. When the wireless chargingapparatus 100 performs wireless power transmission, the communicationunit 120 transmits a wireless power transmission request signal fromanother wireless charging apparatus or a wireless power transmitterlocated near the wireless charging apparatus of the present invention inresponse to a wireless power transmission request. Here, thecommunication unit 120 may unicast, multicast, or broadcast the signal.

The TRX module 130 is a wireless power transceiver. When the wirelesscharging apparatus 100 performs wireless power reception, the TRX module130 resonates at the same frequency as that of another wireless chargingapparatus transmitting wireless electric power or of a resonance unit ofa wireless power transmitter of a transmission side through a resonanceunit 140 to receive electric power transmitted from a wireless chargingapparatus of a transmission side or a wireless power transmitter of atransmission side, and forwards the received electric power to thebattery 150.

When the wireless charging apparatus 100 performs wireless power relay,the TRX module 130 stops wireless power reception or wireless powertransmission to wirelessly relay electric power between the wirelesscharging apparatus 100 and another wireless charging apparatus, awireless power transmitter, or a wireless power receiver located nearthe wireless charging apparatus 100 through the resonance unit 140.

When the wireless charging apparatus 100 performs wireless powertransmission, the TRX module 130 transmits electric power in the form ofan AC waveform or converts electric power from a DC form to an AC form,using an inverter to transmit the electric power in the form of an ACwaveform. The TRX module 130 is implemented in the form in which theelectric power is received from an external DC power source to betransmitted or the form in which the electric power is received from thebattery 150 to be transmitted, or is implemented in the form of a powerreception interface to receive electric power externally and supply theelectric power to another component element. It will be appreciated bythose skilled in the art that the TRX module 130 is not limited as longas it includes a unit for providing electric power in a predetermined ACwaveform.

In addition, the TRX module 130 provides an AC waveform through theresonator 140, and may provide an AC waveform in the form of anelectromagnetic field according to another embodiment of the presentinvention. When the TRX module 130 transmits electric power in an ACwaveform through the resonator 140, an inductance L of a loop coil ofthe resonator 140 is changed. Meanwhile, it will be appreciated by thoseskilled in the art that the TRX module 130 may use any unit other thanthe resonator 140 as long as the unit can transmit and receive anelectromagnetic wave.

The resonator 140 is a structure in the form of a coil, and may furtherinclude a capacitor unit configured by a LUMP type cap block.

The TRX module 130 and the communication unit 120 may have differentpieces of hardware such that the wireless charging apparatus 100performs communications in an out-band form. However, according to anembodiment of the present invention, the TRX module 130 and thecommunication unit 120 are implemented using one piece of hardware sothat the wireless charging apparatus 100 performs communications in anin-band form.

The above-described wireless charging apparatus 100 transmits andreceives various signals, and accordingly, a charging operation throughwireless power transmission and reception is performed between wirelesscharging apparatuses, between a wireless charging apparatus and awireless power receiver, or between a wireless charging apparatus and awireless power transmitter.

FIG. 2 is a detailed block diagram of a wireless power transceiver (TRX)module of a wireless charging apparatus, according to an embodiment ofthe present invention.

Referring to FIG. 2, the TRX module 130 includes a Power ManagementIntegrated Circuit (PMIC) 231, a booster Integrated Circuit (IC) 232, afirst switch (SW1) 233, an RX unit 235, a TX unit 237, and a secondswitch (SW2) 239.

The PMIC 231 manages electric power of the wireless charging apparatus.For example, if external electric power (DC) is applied to the PMIC 231,electric power is supplied to component elements of the wirelesscharging apparatus using the external electric power (DC) and thebattery 250 is charged. The PMIC 231 receives electric power receivedfrom the RX unit 235 through the resonator 140, supplies electric powerto the component elements of the wireless charging apparatus, andcharges the battery 150.

When electric power is transmitted by using electric power of thebattery 150, the booster IC 232 adjusts a voltage of the electric powersupplied from the battery to a predetermined voltage to provide thepredetermined voltage. For example, the booster IC 232 may raise avoltage of the electric power provided from the battery 150 to a voltagerequired for power transmission.

When the voltage of the battery is a voltage required for necessaryelectric power or higher, a buck converter IC may be used instead of thebooster IC.

The SW1 233 performs a switching operation between the external powersource DC, and the booster IC 232 and the TX unit 237. For example, theSW1 233 transmits electric power to the TX unit 237 when the wirelesscharging apparatus wirelessly transmits electric power, and interruptstransmission of electric power to the TX unit 237 when the wirelesscharging apparatus wirelessly relays electric power or wirelesslyreceives electric power. The SW1 233 transmits the electric powerreceived from the external power source DC to the TX unit 237 whentransmitting electric power to the TX unit 237, or transmits theelectric power received from the battery 150 through the booster IC 232to the TX unit 237.

The RX unit 235 is a wireless power receiver or may be in the form of awireless power reception board. When the wireless charging apparatus 100performs wireless power reception through the resonator 140, the RX unit235 resonates at the same frequency as that of another wireless chargingapparatus transmitting wireless electric power or of a resonance unit ofa wireless power transmitter of a transmission side through a resonanceunit 140 to receive electric power transmitted from a wireless chargingapparatus of a transmission side or a wireless power transmitter of atransmission side.

The TX unit 237 is a wireless power transmitter or may be in the form ofa wireless power transmission board. The wireless power transmissionboard includes a switch type power amplifier. When the wireless chargingapparatus 100 performs wireless power transmission, the TX unit 237transmits electric power in the form of an AC waveform or convertselectric power from a DC form to an AC form using an inverter totransmit the electric power in the form of an AC waveform whilesupplying electric power in the form of a DC waveform. The TX unit 237receives the electric power received from the external power source DCthrough the SW1 233 or transmits the electric power received from thebattery 150 via the booster IC 232 through the resonator 140.

The SW2 239 performs a switching operation between the RX unit 235 andthe TX unit 237, and the resonator 140. When the wireless chargingapparatus wirelessly receives electric power, the SW2 239 connects theRX unit 235 and the resonator 140 and interrupts connection of the TXunit 237 and the resonator 140. When the wireless charging apparatuswirelessly relays electric power, the SW2 239 interrupts connection ofthe RX unit 235 and the resonator 140 and interrupts connection of theTX unit 237 and the resonator 140. When the wireless charging apparatuswirelessly transmits electric power, the SW2 239 interrupts connectionof the RX unit 235 and the resonator 140 and connects the TX unit 237and the resonator 140.

FIG. 3 is a block diagram of a wireless power receiver unit and awireless transmitter unit according to the embodiment of the presentinvention.

Referring to FIG. 3, the RX unit 235 includes a rectifier 318, a DC/DCconverter 316, a switch 314, and a loader 312. The rectifier 318rectifies wireless AC power received from another wireless chargingapparatus or from a wireless power transmitter into a DC form, and forexample, may be implemented in the form of a bridge diode. The DC/DCconverter 316 converts the rectified electric power into a preset gain.For example, the DC/DC converter 316 converts the rectified electricpower such that an output voltage thereof becomes 5 V. The switch 314connects the DC/DC converter 316 to the loader 312. The switch 314maintains an on/off state under the control of the controller. When theswitch 314 is in an on state, the loader 312 stores the convertedelectric power input from the DC/DC converter 316, and provides thestored electric power to the PMIC 231.

If a power storage unit is not necessary, the loader 312 may be removed.

The TX unit 237 includes a driver 322, an amplifier 324, and a matchingunit 326. The driver 322 outputs DC electric power having a presetvoltage value using the electric power provided from the SW1 233. Thevoltage value of the DC electric power output by the driver 322 iscontrolled by the controller 110 and the communication unit 120.

The DC current output from the driver 322 is output to the amplifier324. The amplifier 324 amplifies the DC current with a preset gain. Inaddition, the DC electric power is converted into AC electric powerbased on a signal input from the controller and the communication unit.Accordingly, the amplifier 324 outputs AC electric power.

The matching unit 326 performs impedance matching such that thetransmission power is transmitted to the reception side. For example,the matching unit 326 adjusts impedance viewed from the matching unit326 and controls the output power to have high efficiency or highcapacity. The matching unit 326 adjusts impedance based on a control ofthe controller 110 and the communication unit 120. The matching unit 326includes at least one of a coil and a capacitor. The controller 110 andthe communication unit 120 controls a connection state with at least oneof the coil and the capacitor, and accordingly, performs impedancematching. The matching unit 326 transmits transmission power through theresonator 140 connected via the SW2 239 according to impedance matching.

Hereinafter, an operation of the wireless charging apparatus 100 will bedescribed as an example.

FIG. 4 is a flowchart of an operation of a wireless charging apparatus,according to an embodiment of the present invention.

Referring to FIG. 4, the wireless charging apparatus 100 determineswhether electric power is wirelessly received, transmitted, or relayedin step 410. For example, the wireless charging apparatus 100 may selecta power transmission mode first, and then may select a power receptionmode or a power relay mode, according to the situation. According toanother embodiment of the present invention, any one of a powerreception mode, a power relay mode, and a power transmission mode may beselected by the user, and any one of a power reception mode, a powerrelay mode, and a power transmission mode may be selected according towhether external DC power is applied or according to a battery residualpower level.

When wireless reception of electric power is selected, the wirelesscharging apparatus 100 controls the SW2 239 such that the RX unit 235and the resonator 140 are connected to each other in step 412. If the RXunit 235 and the resonator 140 are connected to each other, the wirelesscharging apparatus 100 receives electric power from another wirelesscharging apparatus or from a wireless power transmitter through theresonator 140. As the RX unit 235 and the resonator 140 are connected toeach other, the wireless charging apparatus 100 charges the battery 150using the electric power received in step 414.

When wireless relay of electric power is selected, the wireless chargingapparatus 100 controls the SW2 239 such that the RX unit 235 and the TXunit 237 are not connected to the resonator 140 in step 422.

When wireless transmission of electric power is selected, the wirelesscharging apparatus 100 controls the SW2 239 such that the TX unit 237and the resonator 140 are connected to each other in step 432. If the TXunit 237 and the resonator 140 are connected to each other, the wirelesscharging apparatus 100 transmits electric power to another wirelesscharging apparatus or to a wireless power transmitter through theresonator 140.

If the TX unit 237 and the resonator 140 are connected to each other,the wireless charging apparatus 100 determines whether electric power isto be transmitted using an external DC power source or using a batteryin step 434. For example, the wireless charging apparatus 100 transmitselectric power using the external DC power source when the external DCpower source is provided, and transmits electric power using the battery150 when the external DC power source is not provided. According toanother embodiment of the present invention, it may be determinedwhether electric power is to be transmitted by using an external DCpower source or by using a battery according to a selection of the user.

When electric power is transmitted by using the external DC powersource, the wireless charging apparatus 100 controls the SW1 233 suchthat the external DC power source is connected to the TX unit 237 instep 436. If the external DC power source is connected to the TX unit237, the wireless charging apparatus 100 transmits the electric powerfrom the external DC power source to the TX unit 237. The wirelesscharging apparatus 100 wirelessly transmits electric power through theTX unit 237 by using the electric power of the external DC power sourcein step 438.

When electric power is transmitted by using the battery 150, thewireless charging apparatus 100 controls the SW1 233 such that theelectric power of the battery 150 is supplied to the TX unit 237 in step442. For example, the wireless charging apparatus 100 controls the SW1233 such that the booster IC 232 for raising a voltage of the electricpower provided from the battery 150 and the TX unit 237 are connected.If the booster IC 232 and the TX unit 237 are connected to each other,the electric power of the battery 150 is transmitted to the TX unit 237via the booster IC 232.

The wireless charging apparatus 100 wirelessly transmits electric powerthrough the TX unit 237 by using the electric power of the battery 150in step 444.

The SW2 239 for wireless power reception, wireless power relay, andwireless power transmission of the wireless charging apparatus 100 isconfigured in various embodiments.

FIGS. 5 to 7 are block diagrams illustrating an example of a secondswitch of a TRX module of a wireless charging apparatus, according to anembodiment of the present invention.

Referring to FIGS. 5 to 7, the SW2 239 includes two switches 239-1 and239-2. Each of the two switches 239-1 and 239-2 includes a firstterminal connected to the RX unit 235, a second terminal connected tothe TX unit 237, a third terminal connected to a corresponding thirdterminal of the other switch, and a fourth terminal connected to theresonator 240 via a capacitor 241.

Referring to FIG. 5, in each of the two switches 239-1 and 239-2 of theSW2 239, the first terminal and the fourth terminal are connected toeach other when electric power is wirelessly received so that the RXunit 235 and the resonator 240 are connected to each other.

Referring to FIG. 6, when electric power is wirelessly relayed, thethird terminals of the two switches 239-1 and 239-2 of the SW2 239 areconnected to each other such that neither the RX unit 235 nor the TXunit 237 is connected to the resonator 240.

Referring to FIG. 7, in each of the two switches 239-1 and 239-2 of theSW2 239, the second terminal and the fourth terminal are connected toeach other when electric power is wirelessly transmitted so that the TXunit 237 and the resonator 240 are connected to each other.

The capacitor 241 is further provided between the SW2 239 and theresonator 240. The capacitor 241 may be a combination of one or moreserial capacitors and one or more parallel capacitors, and adjusts aresonance frequency of the resonator 240.

Additionally, the SW1 233, for determining whether an external DC powersource is to be used or a battery 150 is to be used during a wirelesspower transmission operation of the wireless charging apparatus 100, isimplemented in various embodiments.

FIGS. 8 and 9 are block diagrams illustrating an example of a firstswitch of a TRX module of a wireless charging apparatus according to theembodiment of the present invention.

Referring to FIGS. 8 and 9, the SW1 232 includes a first terminalconnected to the external DC power source, a second terminal connectedto the booster IC 232, and a third terminal connected to the TX unit240.

Referring to FIG. 8, when electric power is wirelessly transmitted byusing the external DC power source, the SW1 233 connects the firstterminal and the third terminal to supply the electric power of theexternal DC power source to the TX unit 237.

Referring to FIG. 9, when electric power is wirelessly transmitted byusing the battery 150, the SW1 233 connects the first terminal and thethird terminal to supply the electric power of the booster IC 232 to theTX unit 237.

Although not shown, the SW1 233 interrupts supply of electric power tothe TX unit 237 when electric power is wirelessly relayed.

According to the embodiment of the present invention, a plurality ofwireless charging apparatuses 100, which are configured as describedabove, charge each other as they get close to each other.

For example, when the wireless charging apparatus 100 receives electricpower from an external DC power source, it acts as a master wirelesscharging apparatus to communicate at least one slave wireless chargingapparatus nearby. Further, the master wireless charging apparatus maytransmit electric power to at least one slave wireless chargingapparatus nearby to charge the at least one slave wireless chargingapparatus.

When there is provided a plurality of slave wireless chargingapparatuses, the master wireless charging apparatus controls such thatthe slave wireless charging apparatuses receive electric power of themaster wireless charging apparatus according to a predeterminedcondition.

For example, the predetermined condition may be any one of distancesbetween the master wireless charging apparatuses and the plurality ofslave wireless charging apparatuses, remaining battery amounts of theplurality of slave wireless charging apparatuses, and a predeterminedtime interval.

The master wireless charging apparatus controls such that the highestlevel slave wireless charging apparatus is operated in a reception modefor receiving electric power according to a predetermined condition, andif the battery of the highest priority slave wireless charging apparatusis fully charged, the second highest priority slave wireless chargingapparatus is operated in a reception mode for receiving electric power.Then, the slave wireless charging apparatus not operated in a receptionmode are controlled to be operated in a relay mode for relaying electricpower.

FIG. 10 is a block diagram illustrating a charging operation between aplurality of wireless charging apparatuses, according to an embodimentof the present invention.

Referring to FIG. 10, when first, second and third wireless chargingapparatuses 1100, 1200, and 1300 are sequentially stacked, the first tothird wireless charging apparatuses 1100 to 1300 transmit and receivesignals through the communication units 1120, 1220, and 1320,respectively. The first to third wireless charging apparatuses 1100 to1300 exchange information, such as their charging state information (abattery residual lever and the like), information on whether electricpower is to be received, relayed, or transmitted, and information onwhether they receive electric power from the external power source DC,through the communication units 1120 to 1320, respectively. The wirelesscharging apparatus receiving electric power from the external DC powersource is the master wireless charging apparatus 1100, and controlscharging operations of the remaining wireless charging apparatuses 1200and 1300.

For example, when the first wireless charging apparatus 1100 receiveselectric power from external DC power source, it acts as a masterwireless charging apparatus. In this case, the controller 1110 of thefirst wireless charging apparatus 1100, through communications with theslave wireless charging apparatuses nearby, for example, the secondwireless charging apparatus 1200 and the third charging apparatus 1300,controls the charging operations of the slave wireless chargingapparatuses.

For example, the first wireless charging apparatus 1100 determines acharging order of the all of the wireless charging apparatuses 1100 to1300 according to a predetermined condition.

According to an embodiment of the present invention, when the firstwireless charging apparatus 1100 receiving external DC electric power isoperated in a wireless power transmission mode, the first wirelesscharging apparatus 1100 allows a wireless charging apparatus with aremaining battery amount of which is the smallest, to be operated in awireless power reception mode, and allows the remaining wirelesscharging apparatuses to be operated in a wireless power relay mode.

According to another embodiment of the present invention, when the firstwireless charging apparatus 1100 receiving external DC electric power isoperated in a wireless power transmission mode, the first wirelesscharging apparatus 1100 allows the second wireless charging apparatus1200, closest to the first wireless charging apparatus 1100, to beoperated in a reception mode first, and allows the third wirelesscharging apparatus 1300 to be operated in a relay mode. Then, if thesecond wireless charging apparatus 1200 is fully charged, the thirdwireless charging apparatus 1300 is operated in a reception mode and thesecond wireless charging apparatus 1200 is operated in a relay mode.

According to another embodiment of the present invention, when the firstwireless charging apparatus 1100 receiving external DC power source isoperated in a wireless power transmission mode, the remaining wirelesscharging apparatuses 1200 and 1300 perform charging operations whilealternately performing a reception mode and a relay mode for apredetermined period of time.

Although it has been described in the embodiments of the presentinvention that the wireless charging apparatuses are stacked to chargeeach other, it will be appreciated that the wireless chargingapparatuses may be disposed in various methods as long as wireless powertransmission, reception, and relay are possible.

According to various embodiments of the present invention, wirelesspower reception, relay, and transmission can be selectively andconveniently performed by one wireless charging apparatus. Further,according to various embodiments of the present invention, becauseelectric power can be supplied through a battery 150 in addition to anexternal DC power source, the user can conveniently perform wirelesspower reception, relay, and transmission while carrying the wirelesscharging apparatus.

Although various embodiments of the present invention have beenillustrated and described, it will be appreciated by those skilled inthe art that the embodiments of the present invention may be variouslymodified without departing from the spirit and the scope of the presentinvention as defined by the following claims and equivalents.

What is claimed is:
 1. A wireless charging method comprising: selectingat least one of a wireless power reception mode and a wireless powertransmission mode by a wireless charging apparatus; wirelessly receivingelectric power, when the wireless power reception mode is selected; andwirelessly transmitting electric power, when the wireless powertransmission mode is selected.
 2. The wireless charging method of claim1, further comprising: selecting a wireless power relay mode; andwirelessly relaying electric power, when the wireless power relay modeis selected.
 3. The wireless charging method of claim 1, whereinwirelessly transmitting the electric power, when the wireless powertransmission mode is selected, comprises: selecting one of an externalpower source and a battery, when the wireless power transmission mode isselected; wirelessly receiving electric power from the external powersource and wirelessly transmitting the electric power from the externalpower source, when the external power source is selected; and wirelesslytransmitting electric power supplied from the battery, when the batteryis selected.
 4. The wireless charging method of claim 1, furthercomprising: when the wireless charging apparatus receives electric powerfrom an external power source, communicating with at least one slavewireless charging apparatus near the wireless charging apparatus, by thewireless charging apparatus, when the wireless charging apparatus actsas a master wireless charging apparatus; and transmitting the electricpower from the external power source to the at least one slave wirelesscharging apparatus to charge the at least one slave wireless chargingapparatus, by the master wireless charging apparatus.
 5. The wirelesscharging method of claim 4, further comprising: when the at least oneslave wireless charging apparatus corresponds to a plurality of slavewireless charging apparatuses, controlling the plurality of slavewireless charging apparatuses such that the plurality of slave wirelesscharging apparatuses receive the electric power of the master wirelesscharging apparatus, according to a predetermined condition.
 6. Thewireless charging method of claim 5, wherein the predetermined conditionis one of distances between the master wireless charging apparatuses andthe plurality of slave wireless charging apparatuses, remaining batteryamounts of the plurality of slave wireless charging apparatuses, and apredetermined time interval.
 7. The wireless charging method of claim 5,wherein controlling the plurality of slave wireless charging apparatusessuch that the plurality of slave wireless charging apparatuses receivethe electric power of the master wireless charging apparatus, accordingto the predetermined condition comprises: controlling such that ahighest priority slave wireless charging apparatus of the plurality ofslave wireless charging apparatuses is operated in a reception mode forreceiving the electric power of the master wireless charging apparatus,according to a predetermined condition; when a battery of the highestpriority slave wireless charging apparatus is fully charged, controllingsuch that a second highest priority slave wireless charging apparatus ofthe plurality of slave wireless charging apparatus is operated in thereception mode for receiving the electric power of the master wirelesscharging apparatus; and controlling such that the plurality of slavewireless charging apparatuses not operated in the reception mode areoperated in a relay mode for relaying the electric power of the masterwireless charging apparatus.
 8. A wireless charging apparatuscomprising: a resonator; a wireless power transceiver comprising awireless power transmitter configured to perform any one of wirelesspower reception and wireless power transmission through the resonator,based on a selection of at least one of a wireless power reception modeand a wireless power transmission mode; and a controller configured to,when the wireless power reception mode is selected, control such thatelectric power is wirelessly received, and when the wireless powertransmission mode is selected, control such that the electric power iswirelessly transmitted.
 9. The wireless charging apparatus of claim 8,wherein the wireless power transceiver is configured to perform wirelesspower relay, based on a selection of a wireless power relay mode, andthe controller is further configured to control such that, when thewireless power relay mode is selected, the electric power is wirelesslyrelayed.
 10. The wireless charging apparatus of claim 9, wherein thewireless power transceiver further comprises: a wireless power receiver;a wireless power transmitter; and a second switch which, when thewireless power reception mode is selected, connects the wireless powerreceiver and the resonator, and when the wireless power transmissionmode is selected, connects the wireless power transmitter and theresonator.
 11. The wireless charging apparatus of claim 10, furthercomprising: a battery; and a first switch, which connects one of anexternal power source and the battery, and the wireless powertransmitter.
 12. The wireless charging apparatus of claim 11, furthercomprising a booster IC, which adjusts a voltage of the battery to apredetermined value between the battery and the first switch.
 13. Thewireless charging apparatus of claim 11, further comprising a buckconverter IC, which adjusts a voltage of the battery to a predeterminedvalue between the battery and the first switch.
 14. The wirelesscharging apparatus of claim 11, further comprising a Power Management IC(PMIC), which wirelessly receives electric power received by thewireless power receiver to charge the battery.
 15. The wireless chargingapparatus of claim 11, further comprising a charger IC, which wirelesslyreceives electric power received by the wireless power receiver tocharge the battery.
 16. The wireless charging apparatus of claim 8,wherein, when the electric power is supplied from an external powersource, the controller is configured to control such that the wirelesscharging apparatus acts as a master wireless charging apparatus, andcontrol such that at least one slave wireless charging apparatus nearthe master wireless charging apparatus is charged, by transmitting theelectric power to the at least one slave wireless charging apparatus, bythe master wireless charging apparatus.
 17. The wireless chargingapparatus of claim 16, wherein when the at least one slave wirelesscharging apparatus corresponds to a plurality of slave wireless chargingapparatuses, the plurality of slave wireless charging apparatuses arecontrolled such that the plurality of slave wireless chargingapparatuses receive the electric power of the master wireless chargingapparatus, according to a predetermined condition.
 18. The wirelesscharging apparatus of claim 17, wherein the predetermined condition isone of distances between the master wireless charging apparatuses andthe plurality of slave wireless charging apparatuses, remaining batteryamounts of the plurality of slave wireless charging apparatuses, and apredetermined time interval.
 19. The wireless charging apparatus ofclaim 16, wherein the controller is configured to control such that ahighest priority slave wireless charging apparatus of the plurality ofslave wireless charging apparatuses is operated in a reception mode forreceiving the electric power of the master wireless charging apparatus,according to a predetermined condition, when a battery of the highestpriority slave wireless charging apparatus is fully charged, controlsuch that a second highest priority slave wireless charging apparatus ofthe plurality of slave wireless charging apparatus is operated in thereception mode for receiving the electric power of the master wirelesscharging apparatus, and control such that the plurality of slavewireless charging apparatuses not operated in the reception mode areoperated in a relay mode for relaying the electric power of the masterwireless charging apparatus.